SAE to metric conversion?

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windmill john
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Re: SAE to metric conversion?

Postby windmill john » Fri Dec 25, 2020 8:52 am

I think for me, it’s just lack of knowledge.

In my world of fiddling I would assume that the next size up from a 7/8th spanner is 1 inch. I’ve heard of 15/16th so in this case I know, but generally speaking, I’ve no idea if I had a certain size British size spanner in my hand, what the next up or down is. As I say, that’s being brought up on metric tools.

Still wouldn’t know what a thousandth of an inch is in metric without Google, or getting a fractions book out.
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Re: SAE to metric conversion?

Postby Mjolinor » Fri Dec 25, 2020 11:41 am

The ball park for thousandths is ^^^ explained up there. It revolves around 40 and 25, there being approximately 25 mm in an inch.

40 X 25 = 1000
25 mm in an inch therefore 40 thou in a mm.

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Re: SAE to metric conversion?

Postby windmill john » Fri Dec 25, 2020 2:10 pm

Just watched a video. Interesting how the Americans refer to 0.375 as 375 thousandths of an inch and not what I would have said .375 of an inch.

Maybe I should start viewing it differently. Maybe I should sell my soul and buy a 1949 something bike..
http://www.kittos.co.uk
Best roads: 623 Burgos to Santander. A back road to Metz; can't remember which!
Tweety Pie, my F650GS
Ari, my 500 Classic
Gupta, my 350 Bullet.
Sold my Airheads, what an idiot.
Too many bikes have come and gone, trying to be sensible now!

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Re: SAE to metric conversion?

Postby Mjolinor » Fri Dec 25, 2020 2:27 pm

Just watched a video. Interesting how the Americans refer to 0.375 as 375 thousandths of an inch and not what I would have said .375 of an inch.

Maybe I should start viewing it differently. Maybe I should sell my soul and buy a 1949 something bike..
I think you mean 3/8. :)

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Re: SAE to metric conversion?

Postby windmill john » Fri Dec 25, 2020 4:20 pm

I think you mean 3/8. :)

Nooooooooooooo ](*,) ](*,) ](*,) ](*,) :grin:
http://www.kittos.co.uk
Best roads: 623 Burgos to Santander. A back road to Metz; can't remember which!
Tweety Pie, my F650GS
Ari, my 500 Classic
Gupta, my 350 Bullet.
Sold my Airheads, what an idiot.
Too many bikes have come and gone, trying to be sensible now!

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Re: SAE to metric conversion?

Postby John Marshall » Fri Dec 25, 2020 7:04 pm

What about that Messidor,Thermidor, Fructidor malarkey?

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Re: SAE to metric conversion?

Postby Rob Frankhamr » Fri Dec 25, 2020 8:44 pm

What about that Messidor,Thermidor, Fructidor malarkey?
Thankfully that only lasted for 14 years and was abolished by Napoleon Bonaparte... who wasn't French and might, therefore, be considered to have had a modicum on common sense.

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Re: SAE to metric conversion?

Postby Roy Gavin » Sat Dec 26, 2020 3:53 am

I am old enough to have used both systems , and I can see the advantages in both.
I can instantly relate to an inch - width of my thumb,foot- length of my, er, foot, and yard, just a good long step forward, and mile - 1000 paces!
And a imperial thou is just about the smallest size I can measure and work too.
I can relate to ounces, pounds, tons, pints and gallons too.
Only problem was working out quantities in yards, feet an inches, converting that to tons, hundredweights and pounds and multiplying the answer in pounds , shillings and pence, in the days before we had calculators and computers.
But once you had the hang of it , it was a good skill to have. The ability to look at numbers and have your hand just write in the answer is considered mystical, but it is little different to a pianist who looks at a musical score and his hands and fingers just hit the correct key without any conscious thought. Both abilities well worth having, but you will not get either pressing buttons on a calculator or whatever.
But some of the metric dimensions and terminology I doubt if I ever will relate to - just what does a newton look like or do, and most seem to just needlessly complicate a simple calculation.
Try working out in metric units how much extra power, or work, is involved in propelling a 300 kg bike and rider up a 1 in 10 gradient at 100 kph compared to a level road, and then the same with a 660 lbs rig at 60 mph. Simple schoolboy mechanics /mental arithmetic gives you a imperial answer near enough 10.80 HP, but when the question was posed on a forum somewhere even two guys who claimed to be university professor/ lecturers had to convert the metric figures into imperial to get an answer of any relevance!
And it is 7/16 Whitworth + 10 cents which equals 10 mm, 7/16 AF + 10 cents is 1/2".
Last edited by Roy Gavin on Sat Dec 26, 2020 6:33 am, edited 1 time in total.

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Re: SAE to metric conversion?

Postby Mjolinor » Sat Dec 26, 2020 4:04 am

7/16 - 10c :)

The only thing in favour of Metric is that it is universally used in the civilised world.

That alone is enough to ensure the survival no matter how stupid it is in usability terms.

Had we evolved with 8 digits then for sure we would have proper hoverboards by now.

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Re: SAE to metric conversion?

Postby keiththeoutfitter1 » Sat Dec 26, 2020 9:15 am

Roy, a Newton is the force you would feel exerted by an average-sized apple when held in your hand. (For illustrative purposes only, not the scientific definition 🙂) So, ten Newtons would be the force exerted by ten apples, which would weigh about a kilogram.
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Re: SAE to metric conversion?

Postby King Herald » Sat Dec 26, 2020 11:19 am

7/16 - 10c :)

The only thing in favour of Metric is that it is universally used in the civilised world.

That alone is enough to ensure the survival no matter how stupid it is in usability terms.

Had we evolved with 8 digits then for sure we would have proper hoverboards by now.

Petrol has been sold in litres for a couple of decades, yet my car still tells me my efficiency in Miles Per Gallon. :-k

We still use Miles Per Hour on road speeds/signs, despite the metric system taking over in the 70’s.

I was raised in a machine shop, with imperial machinery, much of it pre war, yet most of our drawings came in metric, so had to be converted to inches and thou, and I’ve never used a metric micrometer. I do have a metric Vernier caliper though. :grin:
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Re: SAE to metric conversion?

Postby andyb » Sat Dec 26, 2020 12:39 pm

The definition of a Nautical Mile is a length equal to 1/60 of a degree of arc around a great circle of the earth (ie equator or a line of longitude).
Around a latitude away from the equator they do not correspond to 1/60 of a degree. Which can confuse a lot of people!
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Re: SAE to metric conversion?

Postby Mjolinor » Sat Dec 26, 2020 1:01 pm

The definition of a Nautical Mile is a length equal to 1/60 of a degree of arc around a great circle of the earth (ie equator or a line of longitude).
Around a latitude away from the equator they do not correspond to 1/60 of a degree. Which can confuse a lot of people!
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Which is why you need the latitude to work out the distance.

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Re: SAE to metric conversion?

Postby peter » Sat Dec 26, 2020 1:33 pm

you just need Google to find the distance :grin:
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Re: SAE to metric conversion?

Postby george baker » Sat Dec 26, 2020 1:56 pm

Hi
the big thing about metric is it means people who cant, dont have to use fractions. I can manage fractions and Do, but Young People seem to find it problematical

I flip back and forward between Imperial and Metric most of the time. I just cant cope with Centimertres/ Decimetres

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Re: SAE to metric conversion?

Postby Mjolinor » Sat Dec 26, 2020 1:58 pm

you just need Google to find the distance :grin:
Hmm, no one told Columbus or Darwin about that particular utility.

Bit of an oversight methinks.

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Re: SAE to metric conversion?

Postby peter » Sat Dec 26, 2020 2:13 pm

That's why he thought he was in India and calling the native americans "indians". He should have asked google.
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Re: SAE to metric conversion?

Postby Mjolinor » Sat Dec 26, 2020 2:30 pm

Hmm, Indian is Greek for native. The Indians in India are named after the Indus river. The Indians in the US are named after the Greek for native.

That's as I understand it anyway. CBA to Google, I am still recovering from a serious bout of overeating and am never going to eat anything ever again. :)

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Re: SAE to metric conversion?

Postby John Marshall » Sat Dec 26, 2020 2:43 pm

I recall talking to students back in 1985 who knew exactly what a pint was but had no notion of how many pints there were in a gallon.How they got through a Friday night in the Wheatsheaf in Swindon I never found out.One thing was certain however was after a gallon of 6X the metric coinage just looked like pieces of meaningless metal.

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Re: SAE to metric conversion?

Postby windmill john » Sat Dec 26, 2020 4:28 pm

Okay, I’ve done the maths and judging by the answers on this page, you’re all old gits :grin:

I’m 60. Not an engineer and started fiddling with bikes in 1978; Japanese bikes. Since that day, I’ve dealt metric when it comes to bikes and both with other things.
Not being an engineer, I’ve never dealt with tiny sizes and fractions generally, so inches, mills, cms, feet, miles and the general mix has kept me going.
http://www.kittos.co.uk
Best roads: 623 Burgos to Santander. A back road to Metz; can't remember which!
Tweety Pie, my F650GS
Ari, my 500 Classic
Gupta, my 350 Bullet.
Sold my Airheads, what an idiot.
Too many bikes have come and gone, trying to be sensible now!

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Re: SAE to metric conversion?

Postby Mjolinor » Sat Dec 26, 2020 4:33 pm

Okay, I’ve done the maths and judging by the answers on this page, you’re all old gits :grin:
This is not news.

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Re: SAE to metric conversion?

Postby peter » Sat Dec 26, 2020 5:32 pm

The only imperial size I use is 11/16 and only if it can't be avoided.
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Re: SAE to metric conversion?

Postby DEEP DIVER » Sat Dec 26, 2020 8:28 pm

Good thing I didn't bring up my real early Whitworth spanners. They changed the size specs in the WW2 to save metal.

https://en.wikipedia.org/wiki/British_S ... _Whitworth

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Re: SAE to metric conversion?

Postby Roy Gavin » Sun Dec 27, 2020 2:30 am

Kieth, I know that one newton is the unit of force required to accelerate one kg at the rate of one meter per second, per second.
And that gravity accelerates at the rate of around 9.8 meters per second, per second.
But I just can't relate to newtons , although I appreciate for some there may some relevance and requirement in specialist situations.
One explanation of the imperial systems resilience might be that it was created by practical men for practical use, sometimes it seems the metric system was created just to demonstrate the cleverness of the designers!

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Re: SAE to metric conversion?

Postby windmill john » Sun Dec 27, 2020 9:46 am

I’m sure it applies to many things, but when it comes to mechanics ( read fixing vehicles ) Newton metres are just a name to me. I have my physics O level so know the calculations, but my rear axle nut, 85Nm. That could read 85 potatoes as long as my torque wrench reads in potatoes.

The point I’m making is, many times, you do not need to know maths to use measuring equipment. Maybe that’s a bad thing and stopping me from learning what a thousandth of an inch looks like.
http://www.kittos.co.uk
Best roads: 623 Burgos to Santander. A back road to Metz; can't remember which!
Tweety Pie, my F650GS
Ari, my 500 Classic
Gupta, my 350 Bullet.
Sold my Airheads, what an idiot.
Too many bikes have come and gone, trying to be sensible now!


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